Filament quenching apparatus and process

ABSTRACT

An apparatus and process for producing a substantially nonturbulent stream of cooling gas for quenching a melt extruded filament which comprises a quenching chamber, wherein a melt extruded filament is passed therethrough, and a gas entry chamber, the gas entry chamber being provided with means for introducing a cooling gas. The quenching chamber and the gas entry chamber are separated from each other by a porous, multicellular, polymeric foam diffuser which is capable of diffusing gas entering from the gas entry chamber and permitting the diffused gas to pass therethrough into the quenching chamber as a substantially nonturbulent stream of gas thereby quenching the melt extruded filament and producing greater cross-sectional uniformity in the filament.

United States Patent 72] Inventors David M. Harrison Chester; Thomas E.Miles, Richmond, both of Va. [2 1] Appl. No. 805,261 [22] Filed Mar. 7,1969 [45] Patented Nov. 9, 1971 [73] Assignee Allied ChemicalCorporation New York, N.Y.

[54] FILAMENT QUENCHING APPARATUS AND 45, I76 F, 237; l8/8 QA 5 6]References Cited UNITED STATES PATENTS 3,508,296 4/1970 Ono 18/8 0 A3,389,429 6/1968 Montgomery [8/8 0 A FOREIGN PATENTS 43/19610 8/1968Japan 264/l 76 F Primary Examiner-Jay l-l. Woo Att0rneyRoy H. MassengillABSTRACT: An apparatus and process for producing a substantiallynonturbulent stream of cooling gas for quenching a melt extrudedfilament which comprises a quenching chamber, wherein a melt extrudedfilament is passed therethrough, and a gas entry chamber, the gas entrychamber being provided with means for introducing a cooling gas. Thequenching chamber and the gas entry chamber are separated from eachother by a porous, multicellular, polymeric foam diffuser which iscapable of diffusing gas entering from the gas entry chamber andpermitting the diffused gas to pass therethrough into the quenchingchamber as a substantially nonturbulent stream of gas thereby quenchingthe melt extruded filament and producing greater cross-sectionaluniformity in the filament.

PATENTEUunv 9-19" 3.6 1 9 452 m VIiN'I mes David M. Harrison Thomas E.Miles wow V.

ATTORNEY F ILAMENT QUENCHING APPARATUS AND PROCESS BACKGROUND OF THEINVENTION This invention relates to an apparatus and process for theproduction of a substantially nonturbulent stream of quenching gas forquenching one or more synthetic filaments produced by a melt spinningprocess.

In a typical melt spinning process, one or more filaments extrudes fromone or more spinnerettes and passes into a quenching chamber. Thequenching chamber comprises one or more walls which can be a perforatedplate, screen or both which separates the quenching chamber from anadjoining gas entry chamber which is in communication with a cooling gassupply system. The synthetic polymer extruding from the spinnerette is aviscous liquid at an elevated temperature. Cooling of this liquid takesplace in the quenching chamber where a cooling gas, which is usuallyair, is contacted with the filaments. The cooling gas enters thequenching chamber from the gas entry chamber through the perforatedplate or plates in a direction substantially perpendicular to thefilaments. The filaments pass through the quenching chamber in adirection substantially parallel to the perforated plate or platesseparating the gas entry chamber from the quenching chamber. The use ofthe perforated plate or plates is necessary to reduce cooling gasturbulence because the filaments are highly vulnerable to cooling gasturbulence since they are in the liquid phase at entry into thequenching chamber. Turbulence in the cooling gas stream detracts fromthe uniformity, the orientation capacity, and the strength of thefilaments. When two or more perforated plates are used, the volumebetween the inner and outer perforated plates serves as a plenum chamberto further disperse the cooling gas and reduce its turbulence. Theperforated plates therefore serve the purpose of further dispersing andreducing the turbulence of the cooling gas supplied to the quenchingchamber so that the extruded filaments have more uniform propertiesthroughout their whole length.

The prior art also teaches that the turbulence of the gas stream in thequenching chamber can be reduced by using a number of screen layers ofthe same or different mesh lying against each other in place of or inaddition to the perforated plate or plates. The mesh in the direction ofgas flow can be the same of successively larger or smaller. Great carehas to be exercised to construct such a number of screen layers and thismethod is extremely expensive.

The apparatus and process described above is adequate for low filamentextrusion rates; however, in keeping with the competitive demands of themodern textile industry, higher filament extrusion rates are nowrequired and effective quenching of the filaments is a problem using theconventional apparatus and process described above. For example, whenthe above-described apparatus is used with a high filament extrusionrate and a relatively low cooling gas rate which will produce filamentshaving an acceptable Percent Uster and drawing performance, thefilaments are wound on the takeup package at a relatively hightemperature and excessive package growth may occur with certain polymerswhich produces a loose, sloughing and unacceptable fiber package. On theother hand, when the cooling gas rate is increased to a point where anacceptable fiber package can be produced, the resulting filaments havean unacceptably high Percent Uster with accompanying high wraps andbreaks upon drawing or subsequent processing.

A typical perforated plate which has been used in the prior art hasunder 50 percent open area which consists of small diameter holes spacedat regular centers. A check of the cooling gas velocity through theperforations has shown that the gas turbulence in the quenching chamberis caused by a jetting action of the gas through the perforations. Thisjetting action causes turbulence in the quenching chamber and producesfilaments having nonuniform cross section.

It has now been discovered that a substantially nonturbulent stream ofcooling gas can be produced for quenching a melt extruded filament byseparating the gas entry chamber and the quenching chamber with aporous, multicellular, polymeric foam diffuser which is capable ofdiffusing the cooling gas entering from the gas entry chamber. Theporous, multicellular polymeric foam diffuser diffuses the cooling gasand permits it to pass therethrough into the quenching chamber as asubstantially nonturbulent stream of gas thereby quenching the meltextruded filament and producing a, filament having a more uniform crosssection, a significantly improved Percent Uster and a significantlyimproved drawing performance at high filament extrusion rates.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided an apparatus for producing a substantially nonturbulentstream of cooling gas for quenching a melt extruded filament whichcomprises a quenching chamber wherein a melt extruded filament is passedtherethrough and a gas entry chamber, said gas entry chamber beingprovided with means for introducing a cooling gas. The quenching chamberand the gas entry chamber are separated from each other by a porous,multicellular, polymeric foam diffuser which is capable of diffusingwithin said diffuser gas entering from the gas entry chamber andpermitting said difi'used gas to pass therethrough said diffuser intosaid quenching chamber as a substantially nonturbulent stream of gasthereby quenching the melt extruded filament and producing greatercross-sectional uniformity in said filament at a high filament extrusionrate. The greater cross-sectional uniformity in the filament results ina filament having a more uniform cross section, a significantly improvedPercent Uster and a significantly improved drawing performance.

The term porous, multicellular polymeric foam difiuser used to definethe present invention is to be understood to mean that a sufficientnumber of the foam cells are interconnecting to an extent that the foamis considered to be opencelled and is capable of diffusing gas inaccordance with the present invention.

Accordingly, using the above-described apparatus, there is provided, in.accordance with the present invention, a process for quenching a meltextruded filament which comprises introducing a cooling gas into a gasentry zone and passing the gas from the gas entry zone into a porous,multicellular, polymeric foam diffusion zone. The gas is diffused withinthe porous, multicellular, polymeric foam difi'usion zone and thediffused gas is permitted to pass therethrough the diffusion zone into aquenching zone as a substantially nonturbulent stream of gas. A meltextruded filament is passed through the quenching zone and is quenchedin the quenching zone by the substantially nonturbulent stream ofcooling gas thereby producing greater cross-sectional uniformity in thefilament.

The porous, multicellular, polymeric foam diffuser used in the presentinvention can have a foam thickness, generally perpendicular to the axisof the quenching chamber or apparatus, of about A to 4, preferably aboutA to 2, inches and can have a length, generally parallel to the axis ofthe quenching chamber or apparatus, of about 6 to 72, preferably about 6to 24, inches. The width of the porous, multicellular, polymeric foamdiffuser is determined by the configuration of the filaments in thequenching chamber. The porous, multicellular, polymeric foam can haveabout 50 to 200, preferably about 75 to 150, cells per lineal inch anda'cellular void volume of about 50 to 97, preferably about 75 to 97,percent of the total volume of the porous, multicellular polymeric foam.Accordingly, the polymer volume of the porous, multicellular, polymericfoam can be about 3 to 50, preferably about 3 to 25, percent of thetotal volume of the porous, multicellular, polymeric foam. The bulkdensity of the porous, multicellular, polymeric foam can range fromabout I to l0, preferably about L4 to 6, lb. per cu. ft. The porous,multicellular, polymeric foam diffuser can be made from flexible orrigid foam.

The range of gas velocity flow through the porous, multicellular,polymeric foam diffuser can be about 30 to 120, preferably about 40 to90, SCFM per sq. ft. at a pressure differential across the porous,multicellular, polymeric foam of about 0.15 to 4, preferably about 0.2to 2, inches of water. The humidity of the entering gas can beestablished at any given desired humidity level and a suitable humidityrange can be from about 40 to 95 percent relative humidity at 20 C.

The porous, multicellular, polymeric foam diffuser can be a foamedsynthetic polymer such as a polyurethane foam, a vinyl foam, which canbe produced from a vinyl such as polyvinyl chloride or polyvinylacetate, and the like. Accordingly, the porous, multicellular, polymericfoam diffuser can be a natural or synthetic foam rubber such as acrylic,neoprene, polybutadiene, nitrile, butadiene-acrylonitrile,butadiene-styrene, polyisobutylene, polyisoprene, vinyl pyridine,silicone, and the like.

A particularly advantageous aspect of the porous, multicellular,polymeric foam diffuser used in the present invention is its ability todiffuse cooling gas in three dimensions thereby producingthesubstantially non turbulent stream of cooling gas.

In a preferred embodiment of the present invention, the porous,multicellular, polymeric foam diffuser is a porous, multicellularpolyurethane foam. Polyurethane foams suitable for use in the presentinvention can be produced by reacting an organic compound havingreactive hydrogen atoms and a stoichiometric excess of an organicpolyfunctional isocyanate with water in the presence of a suitablecatalyst and foam stabilizing agent. When water reacts with the excessisocyanate groups not previously reacted, carbon dioxide is formed whichis entrapped in the reaction mixture and thereby causes it to foam. Anauxiliary blowing agent, such as a volatile fluorocarbon, may also beemployed. The polyurethane foam can be produced by the prepolymer methodwherein the organic compound having reactive hydrogen atoms is firstreacted with the organic polyfunctional isocyanate or by the one-shotmethod wherein the reactants are simultaneously mixed together andreacted. The preparation of suitable polyurethane foams is typicallydescribed in US. Pat. Nos. 3,171,820 at columns 1 through 20 and3,198,757 at columns l' through 6. Suitable polyurethane foams useful inthis invention include those of the polyester and polyether type. Aparticularly useful type of polyurethane foam is reticulated polyesterfoam or reticulated polyether foam.

In some cases, it may be desirable to provide a means for producing anadditional pressure drop across the porous, multicellular polymeric foamdiffuser. Such an additional pressure drop can be provided by coveringthe gas intake surface of the porous, multicellular, polymeric foamdiffuser with a cooling gas distribution means such as a woven ornonwoven felt material which can be produced from a natural or syntheticfiber. Suitable fibers include cotton, wool, polyamides, polyesters andthe like. Suitable felt materials can have a total weight of betweenabout to 40, preferably about to 30, oz. per sq. yard. When such a feltmaterial is used, the pressure drop across it is usually about 0.5 to 2inches of water.

The scope of the present invention includes the use of the porous,multicellular, polymeric foam diffuser to diffuse cooling gas in crosscurrent quenching wherein the cooling gas is passed across the extrudedfilament in a direction substantially perpendicular to the filament andis then exhausted; cocurrent quenching wherein the cooling gas is passedinto the quenching chamber and travels in a direction substantiallyparallel to the filament downward through the quenching chamber into andthrough a cooling stack; inflow quenching wherein the cooling gas ispassed into the quenching chamber and travels in a directionsubstantially parallel to the filament downward through the quenchingchamber and is then exhausted after passing therethrough the quenchingchamber; and the like.

The apparatus and process of the present invention can be used to quenchsynthetic filaments such as a polyamide,

polyester, polyolefin, polysulfone, polyphenyloxide, polycarbonate,polyacrylonitrile and the like or polymer. blends thereof.

Suitable polyamides include, for example, those prepared by condensationof hexamethylene diamine and adipic acid, condensation of hexamethylenediamine and sebacic acid known as nylon 6,6 and nylon 6,10, respectivelycondensation of bis(para-aminocyclohexyl)methane and dodacanedioic acid,or by polymerization of -caprolactam, 7-aminoheptanoic acid,B-caprylactam, 9-aminopelargonic acid. 1 l-aminoundecanoic acid, andl2-dodecalactam, known as nylon 6, nylon 7, nylon 8, nylon 9, nylon l l,and nylon 12, respectively.

Suitable polyesters can be prepared in general by condensation reactionsbetween dicarboxylic acids or their derivatives and comounds containingtwo hydroxyl groups, or materials possessing both an alcohol group and acarboxylic acid group or derivative thereof; or by polymerization oflactones. The preferred polyester is polyethylene terephthalate.

DESCRIPTION OF THE DRAWINGS FIG. 1 is cross sectional view showing afiber melt extrusion apparatus and process illustrating the presentinvention which uses a porous, multicellular, polymeric foam diffuser todiffuse filament quenching gas.

FIG. 2 is an illustration showing one embodiment of a porous,multicellular, polymeric foam diffuser and a method of fabrication.

Referring now to FIG. 1, a cooling gas, which is preferably air, whichis introduced into gas entry chamber 1 by appropriate gas transfermeans. Gas entry chamber 1 is formed by outer cylindrical neoprenerubber bellows 2 which surrounds inner cylindrical neoprene rubberbellows 3 in a concentric manner thereby forming an annular gas entrychamber. Cooling gas entering gas entry chamber 1 is passed throughfilter felt 4 and then through perforated metal cylinder 5 into porous,multicellular, polymeric foam difluser 6. Perforated metal cylinder 5distributes the cooling gas entering diffuser 6 into smaller streams.The cooling gas is diffused in diffuser 6 nd enters quench chamber 7 asa substantially nonturbulent stream thereby quenching filaments 8emerging from Spinnerette assembly 9. The cooling gas is ,then passeddownward through quench chamber 7 into and through cooling stack 10 andis exited through suitable exit means (not shown). v

The filaments extruded through spinnerette assembly 9 and quenched inquench chamber 7 are collected on takeup means 11 and then are drawninto yarn. Spinnerette 9 is surrounded by cylindrical wall 12 whichsurrounds and encloses the filaments extruding from Spinnerette 9.Cylindrical neoprene rubber bellows 2 is connected to inner flange 13which is positioned near the bottom of cylindrical wall 12 therebycreating the outer extremity of gas entry chamber 1. Perforated metalcylinder 5 is connected to inner flange 14 which is positioned at thebottom of cylindrical wall 12 thereby forming the inner extremity of theupper part of gas entry chamber 1. The bottom of perforated cylinder 5is connected to outer flange 15 which is positioned at the top ofcooling stack 10 Cooling stack 10 serves as a further cooling chamberfor the quenched filaments and additional cooling of the filaments takesplace within this cylindrical stack.

Inner cylindrical neoprene rubber bellows 3 is connected to the upperpart of cooling stack 10 thereby completing the lower inner extremity ofgas entry chamber 1. Filter felt 4, which can be a woven or nonwovenfelt material, is wrapped around perforated metal cylinder 5 and servesto provide a means for producing an additional pressure drop acrossdiffuser 6 and to filter dust and other undesirable contaminants fromthe cooling gas prior to its entry into quench chamber 7.

Diffuser 6 is inserted against perforated cylinder 5 and is held inplace by flange 17 positioned at the bottom of cylindrical wall 12 andflange 18 positioned at the top of cooling stack 10 thereby completingthe filament quenching apparatus of the present invention.

Referring now to FIG. 2, porous, multicellular, polymeric foam diffuser6 can be cut from porous bulk material or can be fabricated from slabstoclt. When diffuser 6 is fabricated from slab stock and formed into acylinder as shown in FIG. 2, a suitable adhesive can be used to join theends to form diffuser 6. A suitable adhesive for polyurethane foam is afast-drying nitrile adhesive marketed as Cycleweld K-l86 by the ChemicalDivision of Chrysler Corporation.

PREFERRED EMBODIMENTS The following examples illustrate the practice andprinciples of this invention and a mode of carrying out the invention.

EXAMPLE I In the operation of the apparatus in FIG. 1, polycaproamidewas melt extruded at a temperature of 275 C., under a pressure of 2,500p.s.i.g. through 204-orifice spinnerette assembly 9, each of theorifices having a-diameter of 0.022 inch, to produce a 5,500 denierundrawn fiber. The polycaproamide was melt extruded through spinnerette9 at a rate of 45 lbs. per hour.

Cooling air entered gas entry chamber 1 at a temperature of 75 F. and ata rate of I SCFM. The air then passed through filter felt 4 (2 layers of10.5 oz. per sq. yd. cotton felt) and perforated metal cylinder 5 intopolyurethane foam diffuser 6. The air was diffused in polyurethane foamdiffuser 6 and entered quench chamber 7 as a substantially nonturbulentstream thereby cooling the filaments emerging from spinnerette 9. Thecooling air passed downward through quench chamber 7 into cooling stack10 and was exited through a suitable exit means (not shown). Thefilaments travelled vertically downward through quench chamber 7 andcooling stack 10. In this manner, the filaments were quenched by meansof cocurrent quenching. The polyurethane foam diffuser separating gasentry chamber 1 and quench chamber 7 was cylindrical in shape with aninner diameter of 8%inches, an outer diameter of l0- inches, a foamthickness of I inch and a length of 8'/4 inches. The polyurethane foamdiffuser was of the polyester type and had 100 cells per lineal inch, acellular volume of 96 percent of the total volume of the foam and apolymer volume of 4 percent of the total volume of the foam. The rate ofgas fiow through polyurethane foam diffuser 6 was 0.55 SCFM/sq. in. witha pressure differential across the foam of 0 25 inches of water.

The extruded fiber was collected at about 1,800 feet per minute ontakeup means 11 and was then drawn about 4.6 times its extruded lengthto produce a 1,260 denier yarn. The yarn had a relative viscosity of 55,as determined at a concentration of l I grams of polymer in 100 ml. of90 percent formic acid at 25 C. (ASTM-D-789-62T), and a tenacity ofabout 9.0 grams per denier.

The undrawn filaments produced above were tested for cross-sectionaluniformity by measuring the Percent Uster in accordance withASTM-Dl,425-60T and were found to have an average Percent Uster of 5.5.

Polycaproamide was melt extruded and a 5,550 denier undrawn fiber wasproduced in the same manner as described above except that polyurethanefoam diffuser 6 was replaced by a perforated metal cylinder of the priorart which was inserted between perforated metal cylinder 5 and quenchchamber 7 to disperse the cooling air stream in quench chamber 7. Theundrawn filaments produced were tested for crosssectional uniformity inthe same manner as above and were found to have an have an averagePercent Uster of 15.

A comparison of the average undrawn filament Percent Uster of 5.5obtained using the apparatus and process of the present invention withthe average undrawn filament Percent Uster of 15 obtained using aconventional apparatus and process illustrates the very greatimprovement in undrawn filament cross-sectional uniformity of the fiberproduced in accordance with the apparatus and process of the presentinvention.

EXAMPLE 2 In the operation of the apparatus in FIG. I, polycaproamidewas melt extruded at a temperature of 275 C., under a pressure of 2,000p.s.i.g. through a 204-orifice spinnerette assembly 9, each of theorifices having a diameter of 0.022 inch, to produce a 5,500 denierundrawn fiber. The polycaproamide was melt extruded through spinnerette9 at a rate of lbs. per hour.

Cooling air entered gas entry chamber 1 at a temperature of 75 F. and ata rate of I05 SCFM. The air 6 passed through filter felt 4 (two layersof 10.5 oz. per sq. yd. cotton felt) and perforated metal cylinder 5into polyurethane foam diffuser 6. The air was diffused in polyurethanefoam diffuser 6 and entered quench chamber 7 as a substantiallynonturbulent stream thereby cooling the filaments emerging fromspinnerette 9. The cooling air passed downward through quench chamber 7into cooling stack 10 and was exited through a suitable exit means (notshown). The filaments travelled vertically downward through quenchchamber 7 and cooling stack 10. In this manner, the filaments werequenched by means of cocurrent quenching. The polyurethane foam diffuserseparating gas entry chamber I and quench chamber 7 was cylindrical inshape with an inner diameter of 8-% inches, an outer diameter of lO-kinches, a foam thickness of 1 inch and a length of 8'/4 inches. Thepolyurethane foam diffuser was of the polyester type and had 100 cellsper lineal inch, a cellular volume of 96 percent of the total volume ofthe foam and a polymer volume of 4 percent of the total volume of thefoam. The rate of gas flow through polyurethane foam diffuser 6 was 0.48SCFM/sq. in. with a pressure differential across the foam of 0.22 inchesof water.

The fiber was collected at about 1600 feet per minute on takeup means 11and then was drawn about 4.8 times its extruded length to produce a 1260denier yarn. The yarn had a relative viscosity of 55, as determined at aconcentration of l l 5 grams of polymer in I00 ml. of 90 percent formicacid at 25 C. (ASTM-D-789-62T), and a tenacity of about 8.9 grams perdenier.

The undrawn filaments produced above were tested for cross-sectionaluniformity by measuring the Percent Uster in accordance withASTM-D-l425-60T and were found to have an average Percent Uster of 5.3.

Polycaproamide was melt extruded and a I260 denier yarn was produced inthe same manner as described above except that polycaproamide was meltextruded through spinnerette 9 at a rate of only 32 lbs. per hour, thecooling air rate was reduced from I05 SCFM to 75 SCFM, and polyurethanefoam diffuser 6 was replaced by a perforated metal cylinder of the priorart which was inserted between perforated metal cylinder 5 and quenchchamber 7 to disperse the cooling air stream in quench chamber 7. Theundrawn filaments produced were tested for cross-sectional uniformity inthe same manner as above and were found to have an average Percent Usterof 8.5.

A comparison of the average undrawn filament Percent Uster of 5.3obtained using the apparatus and process of the present invention withthe average undrawn filament Percent Uster of 8.5 obtained using aconventional apparatus and process also illustrates the very greatimprovement in undrawn filament cross-sectional uniformity of the fiberproduced in accordance with the apparatus and process of the presentinvention.

Furthermore, this example illustrates that the apparatus and process ofthe present invention produces a 25 percent greater undrawn filamentextrusion rate without any sacrifice in undrawn filament cross-sectionaluniformity and permits higher cooling air rates to be used.

EXAMPLE 3 In the operation of the apparatus in FIG. 1, polycaproamidewas melt extruded at a temperature of 275 C. through a 204- orificespinnerette assembly 9, each of the orifices having a diameter of 0.022inch, to produce a 5500 denier undrawn fiber. The polycaproamide wasmelt extruded through spinnerette 9 at various pressures and rates ascontained in table I nication with the lower portion of said wall andextending toward said takeup means;

means integrating said wall and said diffuser thereby forming adimensionally stable quenching apparatus;

b lo 5 means to supply a pressurized cooling gas to said diffuser.

Coolin ai ntered ga hamb 1 t a temperature f 75 3. The combination ofclaim 2 including a cooling stack in F. and at various rates ascontained in table I below and was Communication with the lower P r i ofSaid diffuser and passed through the filament quenching apparatu itending toward said takeup means; means integrating said cordance withthe present invention in the same manner as in Wall, Said diffuse! andSaid cooling Stack y examples 1 and 2. l0 dimensionally stable quenchingapparatus.

Polycaproamide was also melt extruded in the same manner The combinationof Claim 2 wherein Said P T as above except that polyurethane diffuser 6was ticellular, polymeric foam diffuser has about 10 200 C6llS replacedby a perforated metal cylinder of the prior art which P meal Inch offoam; 3 p ym r ll m f about 3 to 50 was inserted between perforatedmetal cylinder 5 and quench Pmcent based on the total foam Volume; a fbulk chamber 7 to dispel-Se the cooling air stream in quench of about to10 lb. per cu. ft.; and said diffuser has a range of h b i gas velocityflow therethrough said foam of about 30 to I The results of theabove-described fiber extrusions are con- SCFM P 1- ffvat a Pdifferemia' across Said mum of mined in m 1 below about 0.15 to 4 inchesof water.

Table I shows that an improvement in undrawn fiber Per- 20 Thecombmation of l 4 wherein sfiid p i cent Uster and an improvement indrawn yarn properties is ucenulafv Polymeric foam diffuser p f f y fobtained at a relatively low polycaproamide throughput of 32 Polymer:foam Selected from thc group consisting of vinyl lb. per hr. using theapparatus and process of the present infoam and Polyureihane foamvention and this improvement in undrawn fiber Percent Uster 6. Thecombination of claim 5 wherein said polyurethane and an improvement indrawn yarn properties becomes signififoam is polyether foam.

y greater as the p y p i throughput is increased 7. The combination ofclaim 5 wherein said polyurethane to a point where, at a polycaproamidethroughput of 45 lb. per f m is polyether foam was 'f z to a "P' f I 8.The combination of claim 5 wherein said polyurethane pac age us ng t eapparatus an process 0 t e prior art wit foam is reticulated highextrusion and cooling air rates.

ln examples l, 2, and 3, the relative humidity of the air en I Thecombmatilon of claim 4 p i tering gas chamber 1 was 65 percent at Rticellular, polymeric foam diffuser comprises a natural or The coolinggas which is used in the present invention can synthenc foam rubber" beany inert gas, for example, carbon dioxide, nitrogen and the 10. Thecombination of claim 4 wherein said porous, mullike, but preferably isair at about room temperature. ticellular, polymeric foam diffuser isprovided with gas dis- TABLE I Polyeaproamlde throughput, lb. per hr.

Type element Poly- Perforated Poly- Perforated Poly- Perforated urethanemetal urethane metal urethane metal foam cylinder foam cylinder foamcylinder Cooling air rate, s.e.i.m 80 75 120 120 120 Extruder pressure,p.s.i.g 2,000 2,000 2, 000 2, 000 2, 500 Breaks per pound 0. 011 0.0150. 011 0. 115 0. 013 (1) Wraps per pound 0.081 0. 075 0. 064 1. 8800.077 Average percent uster 7. 9 8. 5 8 13 5.7

i It was impossible to produce a processable undrawn fiber package usingthese high extrusion and cooling air rates.

No'i'E.-The target fiber physical properties of the above fibers were anultimate tensile strength of 8.95 gins. per denier and a percentultimate elongation of 16.2. The above fibers fell within an acceptablerange from these target figures.

It is claimed:

1. An apparatus for producing a substantially nonturbulent stream ofcooling gas for quenching a melt extruded filament which comprises aquenching chamber, wherein a melt extruded filament is passedtherethrough, and a gas entry chamber, said gas entry chamber providedwith means for introducing a cooling gas; said quenching chamber andsaid gas entry chamber being separated from each other by a porous,multicellular, polymeric foam diffuser capable of diffusing tributionmeans to provide an additional pressure drop across said diffuser.

11. A process for quenching a melt extruded filament which comprisesintroducing a cooling gas into a gas entry zone; passing said gas fromsaid gas entry zone into a porous, multicellular, polymeric foamdiffusion zone; diffusing said gas within said diffusion zone andpermitting said diffused gas to pass therethrough said diffusion zoneinto a quenching zone as a substantially nonturbulent stream of gas;passing a melt extruded filament through said quenching zone therebyquenching the melt extruded filament in said quenching zone andproducing greater cross-sectional uniformity in said filament.

12. The process of claim 11 wherein the gas is passed through saidporous, multicellular, polymeric foam diffusion zone at a gas velocityflow rate of about 30 to SCFM per sq. ft. at a pressure differentialacross said foam diffusion Zone ofabout 0.15 to 4 inches of water.

13. The process of claim 12 wherein said gas is air.

14. The, process of claim 12 wherein said porous, multicellularpolymeric foam diffusion zone comprises a porous, multicellular,polymeric foam diffuser which has about 50 to 200 cells per lineal inchof foam; a polymer volume of about 3 to 50 percent based on the totalfoam volume; and a foam bulk density of about 1 to lb. per cu. ft.

15. The process of claim 14 wherein said porous, multicellular,polymeric foam diffuser comprises a synthetic polymeric foam selectedfrom the group consisting of vinyl foam and polyurethane foam.

16. The process of claim 15 wherein said polyurethane foam is polyetherfoam.

17. The process of claim 15 wherein said polyurethane foam is polyesterfoam.

18. The process of claim 15 wherein said polyurethane form isreticulated.

19. The process of claim 14 wherein said porous, multicellular,polymeric foam diffuser comprises a natural or synthetic foam rubber.

20. The process of claim 12 wherein said porous, multicellu lar,polymeric foam diffusion zone is provided with gas dispolyester,polyolefin,

tribution means to provide an additional pressure drop across saiddiffusion zone.

21. The process of claim ll wherein said extruded filament is selectedfrom the group consisting of a polyamide,

polysulfone, polyphenyloxide, polycarbonate, polyacrylonitrile andpolymer blends thereof.

22. The process of claim 21 wherein the polyamide is polycaproamide.

23. The process of claim 2] wherein polyethylene terephthalate.

24. The process of claim 11 wherein quenched by means of cocurrentquenching.

25. The process of claim 11 wherein said filament is quenched by meansof cross-current quenching.

26. The process of claim 11 wherein said filament is quenched by meansofinflow quenching.

the polyester is said filament is

2. In combination with a spinnerette assembly and a filament takeupmeans, a filament quenching apparatus which comprises: a wall extendingfrom said spinnerette assembly toward said takeup means; a porous,multicellular, polymeric foam diffuser in communication with the lowerportion of said wall and extending toward said takeup means; meansintegrating said wall and said diffuser thereby forming a dimensionallystable quenching apparatus; means to supply a pressurized cooling gas tosaid diffuser.
 3. The combination of claim 2 including a cooling stackin communication with the lower portion of said diffuser and extendingtoward said takeup means; means integrating said wall, said diffuser andsaid cooling stack thereby forming a dimensionally stable quenchingapparatus.
 4. The combination of claim 2 wherein said porous,multicellular, polymeric foam diffuser has about 50 to 200 cells perlineal inch of foam; a polymer volume of about 3 to 50 percent based onthe total foam volume; a foam bulk density of about 1 to 10 lb. per cu.ft.; and said diffuser has a range of gas velocity flow therethroughsaid foam of about 30 to 120 SCFM per sq. ft. at a pressure differentialacross said foam of about 0.15 to 4 inches of water.
 5. The combinationof claim 4 wherein said porous, multicellular, polymeric foam diffusercomprises a synthetic polymeric foam selected from the group consistingof vinyl foam and polyurethane foam.
 6. The combination of claim 5wherein said polyurethane foam is polyether foam.
 7. The combination ofclaim 5 wherein said polyurethane foam is polyester foam.
 8. Thecombination of claim 5 wherein said polyurethane foam is reticulated. 9.The combination of claim 4 wherein said porous, multicellular, polymericfoam diffuser comprises a natural or synthetic foam rubber.
 10. Thecombination of claim 4 wherein said porous, multicellular, polymericfoam diffuser is provided with gas distribution means to provide anadditional pressure drop across said diffuser.
 11. A process forquenching a melt extruded filament which comprises introducing a coolinggas into a gas entry zone; passing said gas from said gas entry zoneinto a porous, multicellular, polymeric foam diffusion zone; diffusingsaid gas within said diffusion zone and permitting said diffused gas topass therethrough said diffusion zone into a quenching zone as asubstantially nonturbulent stream of gas; passing a melt extrudedfilament through said quenching zone thereby quenching the melt extrudedfilament in said quenching zone and producing greater cross-sectionaluniformity in said filameNt.
 12. The process of claim 11 wherein the gasis passed through said porous, multicellular, polymeric foam diffusionzone at a gas velocity flow rate of about 30 to 120 SCFM per sq. ft. ata pressure differential across said foam diffusion zone of about 0.15 to4 inches of water.
 13. The process of claim 12 wherein said gas is air.14. The process of claim 12 wherein said porous, multicellular polymericfoam diffusion zone comprises a porous, multicellular, polymeric foamdiffuser which has about 50 to 200 cells per lineal inch of foam; apolymer volume of about 3 to 50 percent based on the total foam volume;and a foam bulk density of about 1 to 10 lb. per cu. ft.
 15. The processof claim 14 wherein said porous, multicellular, polymeric foam diffusercomprises a synthetic polymeric foam selected from the group consistingof vinyl foam and polyurethane foam.
 16. The process of claim 15 whereinsaid polyurethane foam is polyether foam.
 17. The process of claim 15wherein said polyurethane foam is polyester foam.
 18. The process ofclaim 15 wherein said polyurethane form is reticulated.
 19. The processof claim 14 wherein said porous, multicellular, polymeric foam diffusercomprises a natural or synthetic foam rubber.
 20. The process of claim12 wherein said porous, multicellular, polymeric foam diffusion zone isprovided with gas distribution means to provide an additional pressuredrop across said diffusion zone.
 21. The process of claim 11 whereinsaid melt extruded filament is selected from the group consisting of apolyamide, polyester, polyolefin, polysulfone, polyphenyloxide,polycarbonate, polyacrylonitrile and polymer blends thereof.
 22. Theprocess of claim 21 wherein the polyamide is polycaproamide.
 23. Theprocess of claim 21 wherein the polyester is polyethylene terephthalate.24. The process of claim 11 wherein said filament is quenched by meansof cocurrent quenching.
 25. The process of claim 11 wherein saidfilament is quenched by means of cross-current quenching.
 26. Theprocess of claim 11 wherein said filament is quenched by means of inflowquenching.